Olivia Carter, School of Psychological Sciences, University of Melbourne
Since the 1960s there has been a growing body of research using controlled psychophysical measures to investigate key perceptual and cognitive alterations induced by psychedelics. This talk will review the changes in conscious state associated with psychedelic drug use, focusing on the effects of two serotonergic hallucinogens: psilocybin and lysergic acid diethylamide (LSD). Considering both my own data and that of other research groups, the talk will prioritise the more common and reliably induced effects obtained through subjective questionnaires and psychophysical measures. The findings are grouped into three broad categories (sensory perception, cognitive function and experiences of unity), and demonstrate that although certain aspects of consciousness are improved or enhanced in the psychedelic state, many of the functional capacities that are associated with consciousness are seriously compromised. This data argues against a unidimensional (i.e., levels-based) framework for understanding consciousness. Furthermore, it shows that research on psychedelic-induced changes in consciousness can make an invaluable contribution to our understanding of consciousness by identifying key dimensions of consciousness and the relations between them.